“Que Sera Sera” is the title of a catchy tune from way back when that means: “Whatever will be will be.” The lyrics go on to say, “the future’s not ours to see.” For anyone reading this who has absolutely no connection to this cultural reference, a more modern term in common use would be: “It is was it is.” The notion of these terms captures a perspective known as “fatalism,” the idea that we humans are powerless to control the future. When you take a fatalistic phrase and add a catchy show tune to it, it’s known as “cheerful fatalism.”

One purpose of science and engineering is to do the best we can to make the best future possible. This is probably why society values our profession; so that we can avoid pitfalls from the past. Just when we think our designs are the best they can be, new technologies and innovations come along that make their way into our codes and standards.

Sometimes groups of people decide to make decisions based on popular understandings that are clouded by opinions. One example is banning the use of natural gas as an energy source for new buildings. The first time I heard this, I thought, “Wow! How are we going to make that work?” I understand the argument for reducing greenhouse gasses, a sometimes-fatalistic topic in itself, but I also remember experiencing an earthquake with natural gas explosions and a city fire that spread partly due to natural gas infrastructure.

In plumbing engineering, the primary design consideration that is affected by uncontrollable factors is storm drainage. Plumbing engineers design storm drainage systems to handle rainfall rates based on a “storm of 1-hour duration and a 100-year return period,” per the IPC Appendix B. What this means is that we design storm drainage systems for storms that have an intensity with a 1% chance of happening on any given day. On top of designing a primary storm drain system, plumbing engineers need to consider what happens if the roof drains get clogged. Building codes, such as the IBC, require that “secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason.”

Looking at Appendix B of the IPC, a conservative design average seems to be around 4 inches per hour for a 100-year storm. For a 50,000 square foot roof, that’s about 125,000 gallons of water weighing over 1,000,000 million pounds!

Appendix B of the IPC

Just in a single hour! If you have ever heard on the news about a roof collapsing, you can have some appreciation for how important secondary overflow systems are. There are important differences between state plumbing codes when it comes to designing emergency overflow systems. Some have changed after recent hurricane events, and some codes allow flexibility to design the system in more than one way. Many times, these specific requirements are in the state amendments to the adopted code.

One looming question becomes: What do future rainfall rates look like? A cheerful fatalist may dance around a light pole with an umbrella like Fred Astaire in the rain, but the plumbing engineer, charged with protecting the public, may take an interest in changes to the built environment. According to the EPA, who have collected data for over a century, rainfall rates in the contiguous United States have increased an average of 0.2 inches per decade. This seems like a reasonable rate of increase that can be handled by code officials in their updates.

The bigger question is how do we design for extreme precipitation? I suppose these are the storms that fall within that 1% of a 100-year storm. If extreme storm events begin to happen at a rate that outpaces the data from 100 years, I suppose code officials could decide to use data for 200-year storms to be more conservative. The truth of the matter is that if temperatures do indeed rise, warmer air holds more water, which does indeed lead to greater precipitation.

Looping back around to the topic of banning natural gas. Plumbing engineers who work in certain jurisdictions are being challenged to employ new technologies such as heat pumps for water heating. If you haven’t heard the terms yet, you may start to hear terms such as “electrification” and “decarbonization.” I’m initially puzzled by the idea that we burn coal or hydrocarbons to produce electricity, so how can it be more efficient to use electricity? I suppose if there is a long-term look at creating infrastructure that is renewable or “clean,” electrification may be the wave of the near future. Building engineers are going to need to look for creative solutions as they design buildings while complying with public policy. We have seen it before with the Leadership in Energy and Environmental Design (LEED) initiative, and it does not appear to be going away.

I think a broad-brush statement for most engineers I know is that we are not total fatalists. Even fewer of us are cheerful fatalists. It’s in our DNA to calculate, analyze and plan. When things don’t go as we planned and we don’t see rainbows day after day, we tend to learn from our mistakes.

It is true, I have heard a few engineers state “It is what it is!” If I was me, at some point, full of vim and vigor, why not invent something that captures potential energy from the storm drainage coming down the pipe, a million pounds in one hour, run it through a turbine and keep the lights on? I’m sure there are many other creative ideas out there being developed and just waiting to be implemented. Who are we to predict? Que Sera – the future’s not ours to see.